sstable: create_links: no need to roll-back on failure anymore
sstable: create_links: no need to roll-back on failure anymore

Now that we use `idempotent_link_file` it'll no longer
fail with EEXIST in a replay scenario.

It may fail on ENOENT, and return an exceptional future.
This will be propagated up the stack.  Since it may indicate
parallel invokation of move_to_new_dir, that deletes the source
sstable while this thread links it to the same destination,
rolling back by removing the destination links would
be dangerous.

For an other error, the node is going to be isolated
and stop operation.

Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@scylladb.com>

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla